Control valve for a jet pump

ABSTRACT

The invention relates to a overflow valve for a device (1) for pumping fuel, in which the device (1) has a supply container for fuel for an internal combustion engine of a motor vehicle, a catchment (6) disposed in the supply container, a fuel pumping assembly (19) that aspirates from the catchment (6) and communicates on the pressure side with the engine, a return line (2) from the engine or a direct branch (33) from the pressure line (20) to the supply container, and a fluid entrainment pump (3) communicating with the return line (2) or the branch and disposed in the supply container, by which pump fuel is pumped into the catchment (6), and the overflow valve (22) closes or opens a overflow opening (4) to the fluid entrainment pump (3). The overflow valve has a spirally shaped spring (12), which holds a closing member (7) and presses it vertically in the direction onto the overflow opening (4).

The invention is based on a overflow valve, which is used as a controlvalve in an apparatus for pumping fuel. The apparatus has a supplycontainer for fuel for an internal combustion engine of a motor vehicle,a catchment disposed in the supply container, a fuel pumping assemblythat aspirates from the catchment and communicates on the pressure sidewith the engine, a return line from the engine or a direct branch fromthe pressure line to the supply container, and a fluid entrainment pumpcommunicating with the return line or the branch and disposed in thesupply container. By means of the fluid entrainment pump, the fuel ispumped into the catchment, and the overflow valve closes or opens aoverflow opening to the fluid entrainment pump.

One such apparatus is known from German Patent Disclosure DE 44 26 667A1. There the overflow opening is closed by a ball, which rests on avalve seat of the overflow opening. Lateral guidance of the ball isaffected via ribs in such a way that the ribs can move only verticallyaway from or toward the overflow opening. The vertical motion is causedby two compression forces oriented counter to one another. Oncecompression force is created by fuel that flows through a jet nozzle ofthe fluid entrainment pump. The other compression force is caused by aspring element. The spring element is L-shaped, and the shorter leg ofthis shape is fastened in a carrier, so that the other, long leg, as aunilaterally fastened spiral spring, presses against the ball.

ADVANTAGES OF THE INVENTION

The overflow valve of the invention in an apparatus for pumping fuel tothe internal combustion engine of a motor vehicle has the advantage thatthe use of a spirally shaped spring makes extremely precise control ofthe fluid entrainment pump possible. The spirally shaped spring has ashallow characteristic curve, which can be adjusted so precisely that avery sensitive control of the fluid entrainment pump can be performed.Uncovering of the overflow opening to allow fuel to flow out of thefluid entrainment pump can be adjusted by means of the type of springand the attendant precision in such a way that a desired pressure in thefluid entrainment pump of between 0.25 and 2.5 bar can be controlled asrequired, with only extremely negligible deviation.

Advantageous features and refinements are recited in the dependentclaims.

One advantageous refinement provides that the spring is integrated inone piece with a securing system. As a result, the labor involved inproducing the spring and installing it is kept low. Furthermore, theone-piece nature of the securing system and the spring makes it possibleto assure a precision fit by way of the production tool. Jointlymanufacturing the spring and securing system means that in the laterinstallation, care need be taken merely for the fastening of thesecuring system. The location of the spring in the securing systemremains assured by adherence to the specified tolerances in manufacture.To that end, the securing system has a base, which is secured to thecatchment by means of a seat provided for it. The base has barbs, forinstance, to prevent unintended loosening in the seat.

The securing system itself preferably has a frame, in the middle ofwhich the spring is disposed. On the one hand, in this way the framestabilizes the spring. On the other, a suspension of the spring thatmakes adequate safety possible in operation is assured. A furtheradvantage of using the frame is the attendant rigidity of the securingsystem. As a result, the securing system becomes invulnerable toimpacts, jarring or other exertions of force of the kind that occur inconventional product ion processes and the attendant transportation andstorage. The high rigidity also makes it possible for such machiningsteps as bending or a heat treatment not to impair the adherence totolerances. A further advantage is obtained in assembly. The frameitself is simple to grasp and to insert into the seat intended for it.Because the securing system is in one piece, there is no need for verycomplicated and tedious fastening of smaller components.

Disposing the spring in the middle of the frame assures that thestability of the frame acts on all sides of the spring. This alsoprovides protection for the spring against damage from outside. Acorresponding embodiment of the base or bases is capable of preventingthe spring from being damaged, for instance if the securing system isunintentionally dropped during assembly. only th e frame and theassociated bases can contact the floor in that case . Th e spring inturn can not strike a flat floor and be damaged in the process. Thisadvantage applies not only to the spring but also to a valve secured tothe spring. Since in the installed state in the apparatus this valve ismeant to be seated on a valve seat, damage to the valve would meanrejection of the product.

In another advantageous feature, the valve, which is the closing memberfor the overflow opening of the fluid entrainment pump, is an umbrellavalve. On the one hand, this permits accurate seating of the umbrellavalve on a valve seat of the overflow opening. on the other, when theumbrella valve lifts from the overflow opening, it is assured that auniform outflow of fuel from the fluid entrainment pump through theoverflow opening is assured. This prevents interfering forces,engendered by imbalanced pressure conditions in the fluid entrainmentpump, which must additionally be compensated for in the control process,from occurring.

In a preferred feature of the umbrella valve, the umbrella valve is madefrom an elastomer. The elastomer has the advantage, because of itselastic deformability, of being capable of adapting precisely to thevalve seat. Thus less stringent demands are made of the production ofthis valve seat than are necessary in other types of valves, such as theknown ball. The elastomer also has the advantage of being capable ofacting as a quasi-damper for the vibration and impacts occurring inoperation of the motor vehicle. This prevents damage to the spring orthe valve street. In the sense of this invention, the term elastomer isunderstood to mean any material that on the one hand is capable of beingresistant to the fuel yet on the other has a flexible behavior.

In a further development of a closing member, an umbrella valve is usedthat has a hard, inelastic inner core, which is coated with anelastomeric material. This may be necessary whenever the closing memberis intended to have a certain rigidity or even hardness that theelastomer itself does not have to a sufficient extent. Other refinementsalso contemplate closing members that comprise partly an elastomer andpartly an inflexible material. The inflexible material, such as a steel,is then fastened in the spring or integrally joined to it, while theelastomer is seated on the valve seat.

In pursuit of a further concept, which may also stand on its own, theoverflow valve can also be used generally as a closing valve systemespecially in the line systems of a motor vehicle. To that end, theclosing valve system has an umbrella valve and a spring. The spring isspirally shaped and holds the umbrella valve approximately in themiddle. For that purpose, both the spring and the umbrella valve areadvantageously embodied as described above.

DRAWING

Further advantageous features, refinements and characteristics are shownin further detail in the accompanying drawing and described in theensuing description.

FIG. 1 shows a detail of an apparatus for pumping fuel to an internalcombustion engine of a motor vehicle with a overflow valve according tothe invention;

FIG. 2 is a schematic illustration of the apparatus and the engine;

FIG. 3 shows an exemplary embodiment of a spirally shaped spring;

FIG. 4 shows an umbrella valve which is inserted in a spirally shapedspring of FIG. 3; and

FIG. 5 shows the umbrella valve of FIG. 4 and the securing system withthe spring of FIG. 3 before they are put together.

FIG. 1 shows a detail of an apparatus 1 for pumping fuel. A fluidentrainment pump 3 is secured to a return line 2. The fluid entrainmentpump has a overflow opening 4, so that via a neck 5 fuel can overflowinto a catchment 6. As the closing member 7, an umbrella valve 9 isdisposed on a valve seat 8 of the neck 5. The umbrella valve 9 in thisversion has an umbrella 10 of an elastomer and a rod 11 secured to itthat is made of metal. The umbrella 10 is mounted on the rod 11, as aresult of which a spirally shaped spring 12, which is joined integrallyto a securing system 13, is held in a fastening point 14. To that end,the rod 11 has a thickened portion 15. This thickened portion 15 mayalso be embodied as an undercut. The elastomer umbrella 10 allowsproduction of the valve seat 8 without excessive production effort andcost. At the same time, because of its adaptability to the valve seat 8,the umbrella 10 provides uniformly tight closing on all sides. In engineoperation, the spring 12 is always under pressure; that is, the overflowopening 4 is open. The spacing between the umbrella 10 and the overflowopening 4 defines the flow rate of the overflowing fuel. This rate is inturn dependent on the pressure that prevails in the fluid entrainmentpump 3. If the engine is not in operation, then the umbrella valve 9rests on the valve seat 8, as shown.

FIG. 1 also shows the securing system 13 with the spring 12 andrespective bases 16. The bases 16 are located in corresponding seats 17,and as a result the securing system 13 is permanently secured in thecatchment 6. With regard to the design of this connection but also otherfeatures of the apparatus, such as the fastening of the fluidentrainment pump, the design of the fluid entrainment pump and theoverflow opening 4, and the mode of operation or disposition of thevarious components, reference is made to the entire contents of DE 44 26667 A1 already cited above as prior art.

FIG. 2 shows the apparatus 1 for pumping fuel in its entirety in asimplified view. The apparatus 1 has a supply container 18 for the fuel.The catchment 6 is disposed in this supply container 18. By means of afuel pumping assembly 19, the fuel is carried to the engine 21 via apressure line 20. Unused excess fuel is returned to the supply container18 via the return line 2. The fluid entrainment pump 3 at the end of thereturn line then has a pressure, in the flow nozzle not shown in thisview, that is advantageously varied via the selection of the overflowvalve 22 in such a way that the catchment 6 is always adequately filledwith fuel. Dashed lines also indicate a direct branch 33 from thepressure line 20; the fluid entrainment pump would then be located alongwith the overflow valve in the extension of the branch 33.

FIG. 3 shows the securing system 13 with the integrated spirally shapedspring 12 in an oblique view. The securing system 13 has a frame 23, inthe middle of which the spring 12 extends. The spring 12 in thisembodiment has a course 24 that extends in a spiral from an edge 25 ofthe frame 23 to a center point 26. Both the spring and the entiresecuring system 13, in this embodiment, are made from a spring steel,for instance by erosion or stamping. To allow a pressure to be exertedin the vertical direction through the spring 12, this springadvantageously has a shape such that it reinforces this verticalexertion of force. To that end, the course 24 may have beveled sides.The spring 12 is also not disposed in a single plane but extendsthree-dimensionally, as is more clearly seen from the following FIG. 4.

FIG. 4 shows the securing system 13 on FIG. 3, and whose center point 26and umbrella valve 26 is now disposed. The umbrella valve 27 is madeentirely of an elastomer, so that its rod 28 and umbrella 29 are in onepiece. The rod 28 has a bellied area as its thickened portion 30. Thethickened portion 30 acts as a counterpart to the umbrella 29 for thespring 12, in order in this way to create a fastening point 31 for thespring. As also seen in FIG. 4, the inserted umbrella valve 27 isshielded by the securing system 13 in such a way that damage to theumbrella 29 is maximally avoided. To that end, bases 32 of the securingsystem 13 are at least as long as the distance by which the umbrella 29protrudes away from the fastening point 31. The frame 23 is also largerthan a diameter of the umbrella 29, so that lateral protection for theumbrella is also provided.

FIG. 5 shows the securing system 13 and the umbrella valve 27 of FIG. 4before the 2 are put together. The rod 28 is embodied in the form of amandrel and is inserted through a center opening 33 in the spring 12. Inthe region of the center opening 33, the spring 12 has a conicalinternal shape, so that if the rod 28, already partly inserted throughthe center opening 33, is pulled farther the thickened portion 30 iscompressed to such an extent that it passes through the center opening33. The conical shape acts at the same time as a barrier, which preventsthe rod 28 from being pulled back through the center opening 33 again inthe opposite direction by the thickened portion 30. The retention of theumbrella valve 27 in the center opening 33 offers the advantage not onlyof simple installation but also that friction, of the kind known inother systems comprising a closing member and a spring, is omitted. Thislack of friction by means of the quasi-internally seated umbrella valve27 reinforces the high sensitivity of this type of control, which makesit possible for the normal deviations in springs, which are in the rangebetween ±5 N, to be reduced by at least one power.

What is claimed is:
 1. A overflow valve (22) for a device (1) forpumping fuel, in which the device (1) has a supply container (18) forfuel for an internal combustion engine (21) of a motor vehicle, acatchment (6) disposed in the supply container (18), a fuel pumpingassembly (19) that aspirates from the catchment (6) and communicates onthe pressure side with the engine (21), a return line (2) from theengine (21) or a direct branch (33) from a pressure line (20) to thesupply container (18), and a fluid entrainment pump (3) communicatingwith the return line (2) or the branch and disposed in the supplycontainer (18), by which pump fuel is pumped into the catchment (6), andthe overflow valve (22) closes or opens a overflow opening (4) to thefluid entrainment pump (3), characterized in that the overflow valve(22) has a spirally shaped spring (12), which holds a closing member (7)and presses it vertically in the direction onto the overflow opening(4).
 2. The overflow valve (22) of claim 1, characterized in that thespring (12) is integrated in one piece with a securing system (13). 3.The overflow valve (22) of claim 2, characterized in that the securingsystem (13) has a base (16; 32), which is secured to the catchment (6)by means of a seat (17) provided for it.
 4. The overflow valve (22) ofclaim 1, characterized in that the securing system (13) forms a frame(23), in the middle of which the spring (2) is disposed.
 5. The overflowvalve (22) of claim 1, characterized in that the closing member (7) isan umbrella valve (9; 27).
 6. The overflow valve (22) of claim 5,characterized in that the closing member (7) has elastomer.
 7. Theoverflow valve (22) of claim 5, characterized in that the closing member(7) is of elastomer.
 8. The overflow valve (22) of claim 5,characterized in that the control valve (9; 27) has a centrally mountedrod (11; 28), which has a thickened portion (15; 30) above a fasteningpoint (14; 31) of the umbrella valve (9; 27) to the spring (12).
 9. Theoverflow valve (22) of claim 1, characterized in that the spring (12)has a centrally mounted middle opening (33) as the fastening point (14;31) for the umbrella valve (9; 27).
 10. The overflow valve (22) of claim1, characterized in that the spring (12) and the umbrella valve (27) areeach in one piece.